Sep 3, 2014

Just last week AMD took the opportunity to announce the latest Radeon R9 285 graphics card (or Tonga) with the occasion of its “30 Years of Radeon Graphics and Gaming Commemoration” event.

And a few days later, the new GPU, which arrives with improved GCN architecture and several other enhancement and pleasant surprises (like Mantle or DirectX 12 support), has been officially unleashed into the wild. Even if it was previously said that Tonga was to be AMD’s answer to NVIDIA’s super-efficient GM107 architecture, the truth turns out to be a little bit different, as Radeon R9 285 is actually just an incremental update from Tahiti. So, the new card retains the same great gaming performance skills and also brings to the table some technological enhancements we have also seen with Hawaii cards like TrueAudio, improved L2 cache and reconfigured compute architecture. But most importantly, Tonga is here to refine the GCN architecture which came with Tahiti and is two and a half years old.

Now for the more technical aspects of the card, the new Radeon R9 285 comes equipped with 28 Compute Units, which translates into a total of 1792 stream processors, 112 texture mapping units and 32 raster operation units. The card has just 2GB VRAM that works beside a 256-bit bus interface and we use the word “just” as we compared it to the Tahiti cards that come with 3GB VRAM (384-bit bus). So what’s the reason for the apparent downgrade? AMD wants to limit the need for a higher memory bus by cutting down on the load imposed on the memory bandwidth. AMD has bundled the GCN architecture with the Color Compensation algorithm, which will supposedly bestow 40% higher memory bandwidth efficiency. This can be achieved because of the technique used, which implies storing the color data from the frame buffer in a lossless compressed format in order to deliver more bandwidth output in gaming tasks.

So overall, the new card performs better than the Tahiti cards. The clock speeds remain at 918 MHz core and 1375 MHz (5.50 GHz effective) clock for the memory. Nevertheless, AMD throws in an updated instruction set which brings about 16-bit floating point and integer instructions that strive for low power compute and media processing. As for software, Tonga is granting support for DirectX 11.2, DirectX 12, Mantle API, TrueAudio, XDMA Crossfire technology and H.264/AVCHD media transcoding for faster media processing at 4K to 720p. AMD also makes public the pricing for the Radeon R9 285 graphics card, which is set to start selling for $249 / €190.